I suspect there is lots of frustration from the BTC vets at the glut of alt-coin as of late. With that said, I'll cut against the grain, and open a thread on the subject, just to see if I'm on track.

As a base point, I understand that one of the big complaints about new alt-coin is "pre-mined" coin whenever a new alt-coin is announced. This is based on the fact that if someone mines a billion joe-coin then makes a big splash about how cool joe-coin is, then eventually JOC / BTC might be exchangeable. Even if that happens at the rate of 1 JOC to 0.00000001 BTC, the fact that Joe is hording one billion JOC, he has now just minted 10 BTC simply by posting some big BS splash on some forum.

Now that we've covered the CON in the Alt-Coin space, let me see if I can try to name the Alt-Coins and enumerate (open to discussion) any virtue in them (other than of course BTC).

BTC - The big brother of the Alt-Coin world. BTC has many assets that I won't take time to enumerate. Transaction fees are now at about 0.9 cents per transaction. Confirmation time is anywhere from seconds (to see the TX on a node) to an hour (to get 6 conf). Mining is done by ASICs specifically designed to mine BTC. I don't know how many BTC were pre-mined (if any).

LTC - Litecoin was developed (I think) as a mining alternative to BTC. Once ASIC mining hit the scene, mortals could no longer mine BTC, and that was left to the ASIC designers fabing ASIC specific to the task. Litecoin uses Scrypt (I think) which means that ASICs are less sutable for the task. So all the BTC mortals that still have GPUs can use the GPUs to mine Litecoin. Litecoin also has quicker confirmations so the confirmation time is anywhere from seconds (to see the TX on your node) to 10 minutes ( to receive 4 conf). TX fees on LTC are steep for Alt-coins, about 5.5 cent per transaction. I don't know how many LTC were pre-mined (if any).

FTC - Don't know why Feathercoin was minted. It is similar in most ways (if not all ways) to LTC. One major difference is that it gives 4x the bounty on mining, but that is just moving a decimal point really. FTC does lower the TX fee compared to LTC. The TX fee for FTC is 0.038 cents per transaction making FTC useful for micro donations perhaps. I don't know how many FTC were pre-mined (if any).

NMC - Namecoin is a coin who's nodes, or perhaps miners, participate in a distributed DNS service (I think). So holding NMC and running a client or miner (perhaps) allows you to run a Dot-bit domain, for example www.bitcointalk.bit .

DVC - Devcoin is intended as a merit token for opensource, sharesource, freesource projects. I think the hope of the project is that ownership of DVC will signify your UBER status at the local Linux conference. Perhaps in the future they can tie upstream commits to kernel.org to DVC payouts, but since DVC is already traiding against BTC, it is now real-ish in value which perhaps reduces its usefulness as a merit badge, since it can be bought.

XPC - Ripple (coin) is an enigma. I went through the "What is Ripple" stuff and it sounded like it was written by a marketing VP. It also violated the first rule of Alt-Coin and pre-mined a billion or so ripples (XPC). 17,000 ripples can now buy one BTC, or 17 XPC to 1 mBTC. So to summarize, that pre-mined billion XPC now appears to be worth $5,000,000 USD, just since they announced. The XPC group has offered to give all the pre-mined coin to charity, but I don't think that has happened in totality yet. To back away from the pre-mined bashing, XPC does do some cool things, if I understand it (which I don't). It deals in debt. How the debt brokering is done I won't go into (since I don't get it). It also keeps balances in fiat currencies. So if someone gives you $10 USD on the ripple network, you have $10 USD on the ripple network. In theory, you can take that to a Ripple Gateway and turn it into $10 off the the ripple network. Also, Ripple maintains a distributed exchange (which is cool). If I have USD, and I want BTC, I put in a BID for BTC based in USD. That bid is sent out to the the network and floats out there. If someone wants to put out an ASK to sell their BTC to USD they do the same procedure and an ask is broadcast. Now you effectively have an order board just like Mt.Gox or any other exchange. If any BID and ASK intersect the sale goes through. If you see your ASK is very close to a BID, you make just UP your bid to intersect with the ASK and get your BTC.

I haven't figured out what the other coins do yet, if anything. Most are variations in economic principles. BTC and LTC are based on processing power. He with the most hashes earns the most. Other coins work off of strait interest, or Proof-of-Stake. If you hold coin, you periodically earn coin based on your holdings. Others are the opposite (called dumerage [sp]). This is like the IRS.. You are taxed (virtually) on your holdings. This encourages you to continually move holdings which (in theory) keeps the money supply dynamic.